Recent years have seen many various kinds of demands placed on memory IC chips. There have been demands for a memory IC to have a multiport capability, various ways of accessing and scanning, and requirements for high memory capacity and high speed processing. To meet these demands, a memory and another element to work as a memory and can access dual-port memory, field memory, orthogonal memory or the memory or a Region of Interest ("ROI") have been provided or proposed in the following references:
(1) "Exclusive DRAM Placing Emphasis on User's Demand", Nikkei Electronics, May 2, 1988.
(2) "Exclusive DRAM is the Big Trend Involving in Standard Product", Nikkei Electronics, Jun. 12, 1989.
(3) Mori, et al. "Image Memory for Graphics Using Rectangle Area Access", The Journal of the Institute of Electronics, Information and communication Engineers, March, 1989.
(The titles above are translations.)
As such, each memory serving a special demand has a simple function. A memory IC with multiple functions does not exist. Such a memory is expensive as compared with the standard DRAM.